1. Field of the Invention
This invention relates to atmosphere concentration monitoring for monitoring the concentrations of one or more specific substances in the atmosphere of a substrate processing apparatus, and to life determination for determining the end of life of an atmosphere processing unit of the substrate processing apparatus.
2. Description of the Related Art
In a substrate processing apparatus used to process substrates for fabricating semiconductor wafers, liquid crystal panels and the like, the concentration of various chemical substances in the atmosphere of the apparatus (alkaline, acidic, organic and other components) must be kept as low as possible. In practice, the concentrations of the chemical substances in the apparatus atmosphere (hereinafter frequently called "atmosphere concentrations") are reduced with an atmosphere processing unit using a filter such as chemical filters and activated charcoal filters. A monitor system for monitoring the atmosphere concentrations is also sometimes used.
In some instances it is desirable to monitor the atmosphere concentrations at multiple locations in a single substrate processing apparatus, while in others a need arises to monitor the atmosphere concentrations at multiple locations in two or more substrate processing apparatuses. More often than not, however, the concentration range over which a specific substance must be measured differs among multiple measurement points. This means that different sets of measurement conditions need to be established at the different points. The prior-art atmosphere concentration monitoring systems are of no use in such cases because they cannot effect measurement under different sets of conditions at multiple locations.
In still other cases, measurement using different sets of measurement conditions at a single measurement point may be desirable. This is difficult with the prior-art atmosphere concentration monitoring systems, however, since they cannot easily effect measurement under different sets of conditions at a single measurement point.
The efficiency of the atmosphere processing systems goes down as they process the atmospheric gas, which is air in many cases. The filters of the atmosphere processing systems are to be replaced when their lifetime has passed, accordingly. Since there has been no good technique to determine the end of the life of the atmosphere processing systems, the filters are often replaced with new ones even when their lifetime still remains.